It's opensource computer hardware or I can simply discribe it as microcontroller for everyone.i.e anyone can learn this without any pre requisites. For more information on this please refer www.arduino.cc

Yeah you can use 2 or more sensors. Or if u want you can use a raspberry pi with camera to calculate maximum colour and then that info van be sent to neopixel LED. For PC you can use some vbscript to give colour values over serial port and then using that colour info to neopixel led.

Yes. Of course, you can use nrf24l01. This uses SPI communication between the microcontroller and the NRF24L01 module. This will help you to increase the range of your plane. There are many libraries like Radiohead library, RF24 library etc. Code part will remain same you can replace the virtual wire library to RF24 library and send the data through the SDO or MOSI pin etc.

Hi Michal Choma, Thanks for your comments. The bright part of the dotted lines are nothing but fringes of diffraction pattern. You can refer this : http://physicsed.buffalostate.edu/pubs/StudentIndepStudy/EURP09/Young/Young.html

Hey, you can check the wireless connectivity between Tx and Rx like this, once you power up both Tx and Rx side , Rx LED of arduino nano turns on or blinks as data it receives data. Check the data pin connections of both RF modules. Pin no 11 in receiver side and 12 in transmitter side.